Sulfate free surfactants (cleansing agents) gently remove surface build up without stripping color. It may be necessary to shampoo twice if the hair has excessive build up. You will know the hair is clean when you achieve a good lather. Once the shampoo lathers follow with Instant Reconstructor. A clean hair shaft can be reconstructed inside out. A balanced PH of 4.5 to 5.5 and sulfate free cleansers are the key to long lasting color. Your will experience clean easy to style free of build up hair. You will no longer experience bad hair days. Often times individuals whom have had negative reactions to various shampoos (skin irritations, flaking or dry scalp, etc.) will notice those problems subside when using sulfate free shampoo.